Some enclosed environments, such as the passenger compartment of a reconnaissance vehicle, require filtered and conditioned air for the comfort and safety of the compartment inhabitants. Such a vehicle is typically provided with an air supply and conditioning system. The air supply and conditioning system filters, pressurizes, and regulates the temperature of the air. The air is pressurized above ambient pressure to protect the compartment inhabitants by ensuring that any air leakages flow from the compartment. The system may be equipped with a blower to provide air for respiration when the power supply (and the air supply and conditioning system thereby) of the vehicle is shut down.
Generally, the air provided to the enclosed environment is supplied at a desired temperature. Some air supply and conditioning systems, however, have limited power to provide the air at the proper temperature. In cold environments, a system may not have enough energy to sufficiently heat the air provided to the enclosed environment. In warmer environments, a system may not provide enough air flow to properly cool the enclosed environment.